1. Field
Subject matter disclosed herein relates to calibrating a glucose monitoring sensor and/or an insulin delivery system including, by way of example but not limitation, calibration that is at least partially automatic and/or a calibration of sensor current measurements during operation.
2. Information
The pancreas of a normal healthy person produces and releases insulin into the blood stream in response to elevated blood plasma glucose levels. Beta cells (β-cells), which reside in the pancreas, produce and secrete insulin into the blood stream as it is needed. If β-cells become incapacitated or die, a condition known as Type I diabetes mellitus (or in some cases, if β-cells produce insufficient quantities of insulin, a condition known as Type II diabetes), then insulin may be provided to a body from another source to maintain life or health.
Traditionally, because insulin cannot be taken orally, insulin has been injected with a syringe. More recently, the use of infusion pump therapy has been increasing in a number of medical situations, including for delivering insulin to diabetics. For example, external infusion pumps may be worn on a belt, in a pocket, or the like, and they can deliver insulin into a body via an infusion tube with a percutaneous needle or a cannula placed in subcutaneous tissue.
As of 1995, less than 5% of Type I diabetics in the United States were using infusion pump therapy. Presently, over 7% of the more than 900,000 Type I diabetics in the U.S. are using infusion pump therapy. The percentage of Type I diabetics that use an infusion pump is growing at a rate of over 2% each year. Moreover, the number of Type II diabetics is growing at 3% or more per year, and growing numbers of insulin-using Type II diabetics are also adopting infusion pumps. Additionally, physicians have recognized that continuous infusion can provide greater control of a diabetic's condition, so they too are increasingly prescribing it for patients.
A closed-loop infusion pump system may include an infusion pump that is automatically and/or semi-automatically controlled to infuse insulin into a patient. The infusion of insulin may be controlled to occur at times and in amounts that are based, for example, upon blood glucose measurements obtained from an embedded blood-glucose sensor in, e.g., real-time. Closed-loop infusion pump systems may also employ the delivery of glucagon, in addition to the delivery of insulin, for controlling blood-glucose and/or insulin levels of a patient (e.g., in a hypoglycemic context).